mirror of
https://github.com/vercel-labs/scriptc.git
synced 2026-11-02 07:43:42 +08:00
Chris Tate
b8e678b765
events.once(process.stdout, name) with a name typed "drain" returned the pending promise without evaluating the name, so a call or comma expression producing "drain" never ran. A name that is not a string literal now runs before the promise is created. A write completion callback that returns a value (`() => count++`, a stored function typed `(): number`) reported SC2020. The stream ignores the return value, so such a callback is adapted to return nothing, as before the error-argument form was added. The stream-shims npm case compiles and matches Node now that write callbacks take the error argument, so its SC2020 expectation is removed.
67 lines
2.2 KiB
TypeScript
67 lines
2.2 KiB
TypeScript
// Writable.write completion callbacks that take the error argument: null
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// after a successful write, the _write failure, ERR_STREAM_WRITE_AFTER_END
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// after end(), and ERR_STREAM_DESTROYED after destroy(). Node orders the
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// callback and the 'error' event through its writable state machine; this
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// program prints both.
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import { Writable } from "node:stream";
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function show(label: string): (error?: Error | null) => void {
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return (error) => {
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const code = error ? (error as NodeJS.ErrnoException).code : undefined;
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console.log(
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label,
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error === null ? "null" : error === undefined ? "undefined" : `${code ?? ""} ${error.message}`,
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);
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};
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}
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const sink = new Writable({
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write(chunk: Buffer, _encoding: string, callback: (error?: Error | null) => void): void {
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callback(chunk.toString() === "bad" ? new Error("rejected") : null);
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},
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});
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sink.on("error", (error) => console.log("error event", error.message));
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sink.write("good", show("good"));
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sink.write("bad", show("bad"));
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const ended = new Writable({
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write(_chunk: Buffer, _encoding: string, callback: (error?: Error | null) => void): void {
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callback();
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},
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});
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ended.on("error", (error) =>
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console.log("ended error event", (error as NodeJS.ErrnoException).code),
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);
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ended.write("first", show("first"));
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ended.end();
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ended.write("late", show("late"));
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const destroyed = new Writable({
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write(_chunk: Buffer, _encoding: string, callback: (error?: Error | null) => void): void {
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callback();
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},
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});
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destroyed.destroy();
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destroyed.write("after destroy", show("destroyed"));
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// A callback declared without parameters keeps its current lowering.
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const plain = new Writable({
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write(_chunk: Buffer, _encoding: string, callback: () => void): void {
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callback();
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},
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});
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plain.write("x", () => console.log("plain done"));
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// Callbacks that return a value: the stream discards it.
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let count = 0;
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const counted = (): number => ++count;
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plain.write("y", counted);
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const tally = (error?: Error | null): number => (error ? -1 : ++count);
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const counting = new Writable({
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write(_chunk: Buffer, _encoding: string, callback: (error?: Error | null) => void): void {
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callback(null);
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},
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});
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counting.write("tally", tally);
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setTimeout(() => console.log("count", count), 5);
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